Tensor product of irreducible characters of $\mathrm{GL}_2(\mathbb{F}_q)$

Abstract

We decompose the tensor product of two irreducible representations of $\mathrm{GL}_2(\mathbb{F}_q)$ for odd $q$ and classify the pairs such that their tensor product is multiplicity free. We also classify the pairs such that their tensor product has unique decomposition property. We additionally characterize the self-dual irreducible representations of $\mathrm{GL}_2(\mathbb{F}_q).$